This invention relates generally to methods, devices, and/or systems for controlling intake to and/or exhaust from an internal combustion engine.
Methods, devices and/or systems that boost intake charge pressure (e.g., defined as force per unit area or energy per unit volume) often extract energy mechanically from a rotating shaft powered by combustion. For example, a turbocharger typically includes a compressor and a turbine attached to a shaft wherein the turbine extracts energy from exhaust, which causes rotation of the shaft, and, consequently, a boost in intake charge pressure (e.g., intake air pressure) by the compressor. As another example, consider a supercharger, which boosts intake charge pressure using a compressor powered by energy extracted from a drive shaft or the like.
Recently, a variety of variable geometry turbochargers (VGTs), that aim to address boost issues, have become available. VGTs, such as, but not limited to, the GARRETT(copyright) VNT(trademark) and AVNT(trademark) turbochargers (Garrett Corporation, California), use adjustable vanes, nozzles or the like, to control exhaust flow across a turbine. For example, GARRETT(copyright) VNT(trademark) turbochargers adjust the exhaust flow at the inlet of a turbine in order to optimize turbine power with the required load. Movement of vanes towards a closed position typically directs exhaust flow more tangentially to the turbine, which, in turn, imparts more energy to the turbine and, consequently, increases compressor boost. Conversely, movement of vanes towards an open position typically directs exhaust flow more radially to the turbine, which, in turn, reduces energy to the turbine and, consequently, decreases compressor boost. Thus, at low engine speed and small exhaust gas flow, a VGT turbocharger may increase turbine power and boost pressure; whereas, at full engine speed/load and high gas flow, a VGT turbocharger may help avoid turbocharger overspeed and help maintain a suitable or a required boost pressure.
A variety of control schemes exist for controlling geometry, for example, an actuator tied to compressor pressure may control geometry and/or an engine management system may control geometry using a vacuum actuator. Overall, a VGT may allow for boost pressure regulation which may effectively optimize power output, fuel efficiency, emissions, response and/or wear. Of course, a turbocharger may employ wastegate technology as an alternative or in addition to aforementioned variable geometry technologies.
Methods, devices and/or systems having functionality, for example, of the aforementioned commercially available devices, and/or other functionality, are described below.